This application claims the benefit of Korean Patent Application No. 2004-0028634 filed on Apr. 26, 2004 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to a wire bonding system and method of use, and more particularly, to a system for and a method of bonding a wire in a multi chip package having an overhang portion.
2. Description of the Related Art
The demand for miniature, thin, and light semiconductor packages has increased to manufacture small electronic devices. A semiconductor package typically includes one semiconductor chip. However, recently, a multi chip package (MCP) in which a number of chips having different functions are stacked in one package has been developed.
In a conventional MCP, a plurality of thin semiconductor chips having different sizes are stacked on each other so that wire bonding of the chips is performed.
When stacking the semiconductor chips for such the above wire bonding, an overhang portion may be formed as shown in FIG. 1.
More specifically, as shown in FIG. 1, in a conventional MCP, a first chip 20 is adhered to an upper side of a circuit board 15, and a second chip 30, larger than the first chip 20, is adhered to an upper side of the first chip 20. The first and second chips 20 and 30 are affixed by an adhesive layer 40 placed to expose a pad portion of the first chip 20. Since the second chip 30 is larger than the first chip 20, an overhang portion A that is not supported by the lower semiconductor chip 20 is formed.
Accordingly, the second chip 30 may bend, or in more serious cases, a crack may appear in the second chip 30 by the contact with a bonding capillary (not shown), when a wire is bonded between the second chip 30 and a printed circuit board (or the first chip 20).
When the chip 30 is thinner and the overhang portion A is longer, the bend or crack becomes more severe. Therefore, there is a need for a wire bonding system and method to avoid these problems.